Iron complex-catalyzed N-arylation of pyrazoles under aqueous medium

Commercially available FeCl3 center dot 6H(2)O with conformationally rigid diamine ligand is a highly effective catalyst for N-arylation of pyrazoles using aryl and heteroaryl iodides. It is notable to show that this complex is tolerable under aqueous medium and particularly the whole reaction utilizes water as the sole solvent without any additional organic co-solvents and surfactants. Attempted study using other nitrogen nucleophiles is described. This newly developed system provides an alternative protocol to Cu- and Pd-catalyzed N-arylation reactions. (C) 2009 Elsevier Ltd. All rights reserved.